我試圖從下面的表從只有那些誰在工作PNO 3,但得到ESSN值不在10SQL 2 WHERE爲同一列的條件
所以結果woud是"666884444"
我試圖做到像
SELECT Essn
FROM WORKS_ON
WHERE Pno = 3 and Pno != 10;
但不能得到正確的結果
WORKS_ON
---Essn-----------Pno-----------Hours----
"123456789" "1" "32.5"
"123456789" "2" "7.5"
"666884444" "3" "40"
"453453453" "1" "20"
"453453453" "2" "20"
"333445555" "2" "10"
"333445555" "3" "10"
"333445555" "10" "10"
"333445555" "20" "10"
"999887777" "30" "30"
"999887777" "10" "10"
"987987987" "10" "35"
"987987987" "30" "5"
"987654321" "30" "20"
"987654321" "20" "15"
"888665555" "20" NULL
是否使用的是RDBMS? – Petaflop
我不認爲我理解一列的值如何可以是3和10. – Deltharis